osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * @OSF_COPYRIGHT@
  32  */
  33 /*
  34  * Mach Operating System
  35  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  36  * All Rights Reserved.
  37  *
  38  * Permission to use, copy, modify and distribute this software and its
  39  * documentation is hereby granted, provided that both the copyright
  40  * notice and this permission notice appear in all copies of the
  41  * software, derivative works or modified versions, and any portions
  42  * thereof, and that both notices appear in supporting documentation.
  43  *
  44  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  45  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  46  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  47  *
  48  * Carnegie Mellon requests users of this software to return to
  49  *
  50  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  51  *  School of Computer Science
  52  *  Carnegie Mellon University
  53  *  Pittsburgh PA 15213-3890
  54  *
  55  * any improvements or extensions that they make and grant Carnegie Mellon
  56  * the rights to redistribute these changes.
  57  */
  58 /*
  59  */
  60
  61 /*
  62  *
  63  *      This file contains routines to check whether an ast is needed.
  64  *
  65  *      ast_check() - check whether ast is needed for interrupt or context
  66  *      switch.  Usually called by clock interrupt handler.
  67  *
  68  */
  69
  70 #include <cputypes.h>
  71 #include <platforms.h>
  72
  73 #include <kern/ast.h>
  74 #include <kern/counters.h>
  75 #include <kern/cpu_number.h>
  76 #include <kern/misc_protos.h>
  77 #include <kern/queue.h>
  78 #include <kern/sched_prim.h>
  79 #include <kern/thread.h>
  80 #include <kern/processor.h>
  81 #include <kern/spl.h>
  82 #include <kern/wait_queue.h>
  83 #include <mach/policy.h>
  84 #include <machine/trap.h> // for CHUD AST hook
  85
  86 void
  87 ast_init(void)
  88 {
  89 }
  90
  91 /*
  92  * Called at splsched.
  93  */
  94 void
  95 ast_taken(
  96         ast_t           reasons,
  97         boolean_t       enable
  98 )
  99 {
 100         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
 101         ast_t                   *myast = ast_pending();
 102         thread_t                thread = current_thread();
 103
 104         /*
 105          * CHUD hook - all threads including idle processor threads
 106          */
 107         if(perfASTHook) {
 108                 if(*myast & AST_CHUD_ALL) {
 109                         perfASTHook(0, NULL, 0, 0);
 110
 111                         if(*myast == AST_NONE) {
 112                                 return; // nothing left to do
 113                         }
 114                 }
 115         } else {
 116                 *myast &= ~AST_CHUD_ALL;
 117         }
 118
 119         reasons &= *myast;
 120         *myast &= ~reasons;
 121
 122         /*
 123          * Handle ASTs for all threads
 124          * except idle processor threads.
 125          */
 126         if (!(thread->state & TH_IDLE)) {
 127                 /*
 128                  * Check for urgent preemption.
 129                  */
 130                 if (    (reasons & AST_URGENT)                          &&
 131                                 wait_queue_assert_possible(thread)              ) {
 132                         if (reasons & AST_PREEMPT) {
 133                                 counter(c_ast_taken_block++);
 134                                 thread_block_reason(THREAD_CONTINUE_NULL, NULL,
 135                                                                                 AST_PREEMPT | AST_URGENT);
 136                         }
 137
 138                         reasons &= ~AST_PREEMPTION;
 139                 }
 140
 141                 /*
 142                  * The kernel preempt traps
 143                  * skip all other ASTs.
 144                  */
 145                 if (!preempt_trap) {
 146                         ml_set_interrupts_enabled(enable);
 147
 148 #ifdef  MACH_BSD
 149                         /*
 150                          * Handle BSD hook.
 151                          */
 152                         if (reasons & AST_BSD) {
 153                                 thread_ast_clear(thread, AST_BSD);
 154                                 bsd_ast(thread);
 155                         }
 156 #endif
 157
 158                         /*
 159                          * Thread APC hook.
 160                          */
 161                         if (reasons & AST_APC)
 162                                 act_execute_returnhandlers();
 163
 164                         ml_set_interrupts_enabled(FALSE);
 165
 166                         /*
 167                          * Check for preemption.
 168                          */
 169                         if (reasons & AST_PREEMPT) {
 170                                 processor_t             myprocessor = current_processor();
 171
 172                                 if (csw_needed(thread, myprocessor))
 173                                         reasons = AST_PREEMPT;
 174                                 else
 175                                         reasons = AST_NONE;
 176                         }
 177                         if (    (reasons & AST_PREEMPT)                         &&
 178                                         wait_queue_assert_possible(thread)              ) {
 179                                 counter(c_ast_taken_block++);
 180                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 181                         }
 182                 }
 183         }
 184
 185         ml_set_interrupts_enabled(enable);
 186 }
 187
 188 /*
 189  * Called at splsched.
 190  */
 191 void
 192 ast_check(
 193         processor_t             processor)
 194 {
 195         register thread_t               thread = processor->active_thread;
 196
 197         processor->current_pri = thread->sched_pri;
 198         if (    processor->state == PROCESSOR_RUNNING           ||
 199                         processor->state == PROCESSOR_SHUTDOWN          ) {
 200                 register ast_t          preempt;
 201
 202                 /*
 203                  *      Propagate thread ast to processor.
 204                  */
 205                 ast_propagate(thread->ast);
 206
 207                 /*
 208                  *      Context switch check.
 209                  */
 210                 if ((preempt = csw_check(thread, processor)) != AST_NONE)
 211                         ast_on(preempt);
 212         }
 213 }